There are a number of essential aspects of non-throttling spray pump mechanisms which have been addressed by prior patents. The first relates to a mechanism for priming the pump during the first use phase of the use of the pump, and the next relates to the pumping mechanism, for the reliable pumping of liquid from the container.
As well known in the art, the manually actuated precompression pump sprayer, otherwise referred to as a pressure build-up pump sprayer, has a reciprocable discharge valve member which opens the discharge at a threshold pump pressure reached during pumping as pump chamber pressure exceeds the force of a return spring. The threshold pressure is not reached to open the discharge while the pump chamber contains air, which is compressible. Thus, for the precompression pump sprayer to function satisfactorily, the pump chamber must first be primed, i.e., the unwanted air in the chamber must be evacuated and replaced by liquid product to be dispensed.
One approach taken in priming the pump chamber of a precompression sprayer is disclosed in U.S. Pat. No. 4,051,983 wherein a longitudinally extending rib or groove is formed on the inner wall of the bore of the pump housing in which the reciprocable discharge valve operates. A nose of the discharge valve, in the form of a popper valve, is normally seated against a discharge valve seat formed in the discharge passage of a hollow piston stem, under the action of an opposing spring force provided by the piston return spring. At the threshold pressure, the popper valve is forced away from its valve seat to open the discharge, in the known manner.
The popper valve has a seal in sliding sealing engagement with the bore in which the valve reciprocates. As the air in the unprimed pump chamber is compressible, the piston and poppet valve are lowered together upon depressing the plunger. At or near the end of the plunger down stroke, the seal between the poppet seal and the wall of the bore in which the poppet operates is interrupted when the poppet seal is juxtaposed to the rib or groove. The air in the pump chamber, which has now been compressed during the piston down stroke, is evacuated from the pump chamber directly into the container via the dip tube extending into the liquid product in the container. The compressed air flows down the tube by capillary action until product partially fills the pump chamber on each ensuing upstroke which draws liquid product into the pump chamber. As liquid product partially fills the pump chamber, it prevents the remaining volume of air in the pump chamber from being evacuated past the popper seal and into the container. This remaining volume of air must now be purged from the chamber to avoid issuance through the discharge orifice causing an undesirable sputtering and uneven spray.
Another approach taken in priming the pump chamber of a precompression pump sprayer is exemplified by U.S. Pat. No. 5,064,105, wherein one or more small protuberances are formed on the wall of the pump chamber. The protuberances deform the piston seal at or near of the end of the piston down stroke, thereby permitting unwanted air from the pump chamber to be evacuated into the container via a side port formed in the pump housing.
A still further arrangement provided for priming the pump chamber is disclosed in U.S. Pat. No. 4,923,094 in which the popper valve has a radially outwardly extending base which, at the end of the plunger down stroke, engages a projection on an inner wall of the closure. The projection forms a priming step for causing a poppet valve seal to shift away from its confronting wall to open a path for evacuating air from the pump chamber into the container via a container vent.
A further system is disclosed in U.S. Pat. No. 5,626,264. According to the patent, the air is purged from the pump chamber through the discharge orifice via the poppet seat seal. A fixed priming ramp, molded in the pump housing, extends toward an end of the discharge valve member in the path of reciprocation so that, at or near the end of the piston down stroke, the lower end of the valve member is deflected to one side by the ramp. The valve member, in the form of a poppet valve normally coaxial with the piston and cylinder, has a conical nose portion in sealing engagement with a discharge valve seat formed in the piston. When deflected the poppet cocks to one side so as to disrupt the discharge valve seal to allow air to escape from the pump chamber to atmosphere via the discharge orifice. On the ensuing upstroke, as the operator releases downward pressure on the plunger head, the piston of the U.S. Pat. No. 5,626,264 patent returns to its FIG. 1 position under the force of the return spring. The poppet is filly reseated, the pump chamber volume expands and suctions product up through the dip tube into the pump chamber. The liquid, under atmospheric pressure in the container that exceeds the sub-atmosphere pressure in the expanding pump chamber, fills the chamber as it by-passes chevron seal 33 at or beyond the end of the valve member upstroke. The liquid may be in-letted to the pump chamber as seal 33 raises slightly out of and/or is forced away from the inner wall of lower cylindrical section 13.
One or two full strokes is described in U.S. Pat. No. 5,626,264, as being sufficient to fully prime the pump. Thus, the approach to pump priming according to the invention may be the sole priming provided for the pump sprayer. It is noted that the sub-atmospheric pressure necessitates the use of a sufficiently strong return spring to counter the progressively increasing vacuum in the container.